JavaScript Data Types

Different type of values

JavaScript variables hold many data types like numbers, strings, objects, booleans and more.

In javascript, a variable can hold many type of values.

Program

<!DOCTYPE html>
<html>
<body>

<script>
var m;           // declare with var keyword,value of m undefine
m = "";           // value of m empty(do not display)
m = 10;           // value of m number
m = 'comsysapp';      // value of m string
alert(m);       // last assign value will be display
</script>    

</body>
</html>

Try in editor

JavaScript typeof

typeof operator check data type of variable, values or expression.

Program

<!DOCTYPE html>
<html>
<body>

<script>
document.write(typeof "");
document.write('');
document.write(typeof "comsysapp");  
document.write('');
document.write(typeof(5.45));
document.write('');
document.write(typeof(5));
document.write('');
document.write(typeof(true));
</script>

</body>
</html>

Try in editor

JavaScript Undefined

If you do not assign value in variable then variable return undefined.

Program

<!DOCTYPE html>
<html>
<body>

<script>
    var myVar;
    alert(myVar);
</script>  

</body>
</html>

Try in editor

About Us

Comsysapp.com is an educational website. Students and software developers can learn programming language tutorials. Comsysapp is very useful for beginners and professional developers. Comsysapp provides tutorial in easy language. Comsysapp.com has focus on simplicity.

Services

Comsysapp.com provides free tutorials like c, html, css, etc. All tutorials are free for beginner and professionals.

Terms of Use

comsysapp.com is not responsible for any mistake. We are not responsible if information made available on our website is incomplete or invalid. But comsysapp.com always try for zero-zero mistake.

Privacy policy

comsysapp.com does not collect any data from users. We use Google AdSense advertising on our website. We never ask personal or private information.

Sitemap

sitemap